‘use client’;

import { useEffect, useRef, useState } from ‘react’;
import { Renderer, Program, Mesh, Triangle, Plane, Texture, RenderTarget } from ‘ogl’;

import ‘./FlexCarousel.css’;

const photo = id => `https://images.unsplash.com/${id}?w=1200&q=80&auto=format&fit=max`;

const DEFAULT_ITEMS = [
{
src: photo(‘photo-1737071371043-761e02b1ef95’),
alt: ‘An iridescent chrome sculpture of a head’,
title: ‘Iridescence’
},
{
src: photo(‘photo-1693645325828-62cd35c8da8f’),
alt: ‘A person in dark clothes standing in front of a white backdrop’,
title: ‘White Room’
},
{ src: photo(‘photo-1739056238917-d89cd05c48d5’), alt: ‘A twisted chrome form on black’, title: ‘Liquid Metal’ },
{ src: photo(‘photo-1747191092806-c7da11881986’), alt: ‘A clay bust shown in profile’, title: ‘Clay Study’ },
{ src: photo(‘photo-1605034313761-73ea4a0cfbf3’), alt: ‘Black and white low top sneakers’, title: ‘Low Tops’ },
{ src: photo(‘photo-1495462911434-be47104d70fa’), alt: ‘A woman in a wide black hat’, title: ‘Brim’ },
{
src: photo(‘photo-1786835568925-20cd20007ed0’),
alt: ‘Three swirling shapes in white, gold and silver on grey’,
title: ‘Three Forms’
},
{ src: photo(‘photo-1770249196550-ff6c641165cb’), alt: ‘A chrome humanoid sculpture’, title: ‘Automaton’ },
{
src: photo(‘photo-1787181875088-087d612262a7’),
alt: ‘A black textured sculpture with an opening at its center’,
title: ‘Obsidian’
},
{
src: photo(‘photo-1770062422885-2dfcbe8fb65b’),
alt: ‘A woman in a white shirt crouching on a dark set’,
title: ‘Poise’
},
{ src: photo(‘photo-1726910133626-9b573eca70ff’), alt: ‘Black curved shapes stacked like a fan’, title: ‘Fins’ },
{ src: photo(‘photo-1604854574958-59047362c165’), alt: ‘A white plaster bust on a black table’, title: ‘Plaster’ }
];

const BEND_PRESETS = {
liquid: {
lensWidth: 0.74,
lensHeight: 1.18,
tilt: 62,
roundness: 1,
bend: 0.34,
reach: 0.38,
curl: ‘twist’,
dispersion: 0.45,
liquid: 0,
followCursor: false
},
ribbon: {
lensWidth: 0.8,
lensHeight: 0.8,
tilt: 0,
roundness: 1,
bend: 0.34,
reach: 0.34,
curl: ‘twist’,
dispersion: 0.4,
liquid: 0,
followCursor: false
},
vortex: {
lensWidth: 0.7,
lensHeight: 0.95,
tilt: 30,
roundness: 1,
bend: 0.46,
reach: 0.3,
curl: ‘twist’,
dispersion: 0.5,
liquid: 0,
followCursor: false
},
arch: {
lensWidth: 0.8,
lensHeight: 0.8,
tilt: 0,
roundness: 1,
bend: 0.3,
reach: 0.36,
curl: ‘rise’,
dispersion: 0.4,
liquid: 0,
followCursor: false
}
};

const FIT_ASPECT = { portrait: 0.75, square: 1, landscape: 4 / 3 };
const TAPS = 12;
const PIXEL_BUDGET = 4.5e6;
const INTRO_DURATION = { rise: 2.1, bloom: 1.6, spin: 2.2, deal: 1.5, fade: 0.35 };

const wrap = (value, size) => ((((value + size / 2) % size) + size) % size) – size / 2;
const clamp01 = value => Math.min(Math.max(value, 0), 1);
const easeOut = value => 1 – Math.pow(1 – clamp01(value), 3);
const easeOutQuint = value => 1 – Math.pow(1 – clamp01(value), 5);
const easeInOut = value => {
const t = clamp01(value);
return t < 0.5 ? 4 * t * t * t : 1 - Math.pow(-2 * t + 2, 3) / 2; }; const cardVertex = `#version 300 es in vec3 position; in vec2 uv; uniform vec4 uRect; uniform vec2 uResolution; out vec2 vUv; out vec2 vLocal; void main() { vUv = uv; vLocal = vec2(position.x, -position.y) * uRect.zw; vec2 px = uRect.xy + vLocal; gl_Position = vec4(px.x / uResolution.x * 2.0 - 1.0, 1.0 - px.y / uResolution.y * 2.0, 0.0, 1.0); } `; const cardFragment = `#version 300 es precision highp float; uniform sampler2D tMap; uniform vec2 uSize; uniform vec2 uImage; uniform float uRadius; uniform float uAlpha; uniform float uReady; uniform float uShift; uniform float uDpr; uniform vec3 uPlaceholder; in vec2 vUv; in vec2 vLocal; out vec4 fragColor; float roundedBox(vec2 p, vec2 b, float r) { vec2 q = abs(p) - b + r; return length(max(q, 0.0)) + min(max(q.x, q.y), 0.0) - r; } void main() { float sd = roundedBox(vLocal, uSize * 0.5, min(uRadius, min(uSize.x, uSize.y) * 0.5)); float mask = clamp(0.5 - sd * uDpr, 0.0, 1.0); vec2 local = vLocal / uSize + 0.5; float cardAspect = uSize.x / uSize.y; float imageAspect = uImage.x / max(uImage.y, 1.0); vec2 scale = imageAspect > cardAspect ? vec2(cardAspect / imageAspect, 1.0) : vec2(1.0, imageAspect / cardAspect);
scale /= 1.08;
vec2 uv = vec2(local.x, 1.0 – local.y);
uv = (uv – 0.5) * scale + 0.5;
uv.x += uShift * (1.0 – scale.x) * 0.5;
vec3 image = texture(tMap, uv).rgb;
vec3 color = mix(uPlaceholder, image, uReady);
float alpha = mask * uAlpha;
fragColor = vec4(color * alpha, alpha);
}
`;

const lensVertex = `#version 300 es
in vec2 position;
void main() {
gl_Position = vec4(position, 0.0, 1.0);
}
`;

const lensFragment = `#version 300 es
precision highp float;
uniform sampler2D tScene;
uniform vec2 uResolution;
uniform float uDpr;
uniform vec2 uCenter;
uniform vec2 uHalf;
uniform float uAngle;
uniform float uExponent;
uniform float uInner;
uniform float uOuter;
uniform float uFlow;
uniform float uCurl;
uniform float uDispersion;
uniform float uStrength;
uniform float uSceneAlpha;
out vec4 fragColor;

void main() {
vec2 frag = gl_FragCoord.xy / uDpr;
vec2 uv = frag / uResolution;
vec2 rel = frag – vec2(uCenter.x, uResolution.y – uCenter.y);
float ca = cos(uAngle);
float sa = sin(uAngle);
vec2 local = vec2(ca * rel.x + sa * rel.y, -sa * rel.x + ca * rel.y);
vec2 k = max(abs(local) / uHalf, vec2(1e-5));
float nd = pow(pow(k.x, uExponent) + pow(k.y, uExponent), 1.0 / uExponent);
vec2 grad = pow(k, vec2(uExponent – 1.0)) * sign(local) / uHalf * pow(nd, 1.0 – uExponent);
float glen = max(length(grad), 1e-6);
float edge = (nd – 1.0) / glen;
vec2 outward = grad / glen;
vec2 normal = vec2(ca * outward.x – sa * outward.y, sa * outward.x + ca * outward.y);
vec2 along = vec2(-normal.y, normal.x);

float t = clamp((edge + uInner) / (uInner + uOuter), 0.0, 1.0);
float ramp = t * t * t * (t * (t * 6.0 – 15.0) + 10.0);
float slope = 16.0 * t * t * (1.0 – t) * (1.0 – t);
float reachX = rel.x / (uResolution.x * 0.5);
float side = smoothstep(0.02, 0.3, abs(reachX)) * (uCurl == 0.0 ? sign(reachX) : uCurl);
float lift = ramp * side * uFlow * uStrength;
vec2 swirl = along * along.y * side * slope * uFlow * uStrength * 0.35;
vec2 drift = vec2(0.0, -lift) – swirl;
vec2 shifted = uv + drift / uResolution;

vec2 texels = uResolution * uDpr;
vec2 gx = dFdx(shifted);
vec2 gy = dFdy(shifted);
gx *= min(1.0, 3.0 / max(length(gx * texels), 1e-4));
gy *= min(1.0, 3.0 / max(length(gy * texels), 1e-4));

vec4 color = textureGrad(tScene, shifted, gx, gy);
vec2 spread = vec2(0.0, side * slope * uFlow * uStrength) / uResolution * uDispersion;
float spreadPx = length(spread * texels);
if (color.a > 0.002 && spreadPx > 0.25) {
vec3 base = color.rgb / color.a;
vec3 sumColor = vec3(0.0);
vec3 sumWeight = vec3(0.0);
for (int i = 0; i < ${TAPS}; i++) { float s = (float(i) + 0.5) / float(${TAPS}); vec4 c = textureGrad(tScene, shifted + spread * (s - 0.5), gx, gy); vec3 w = max(1.0 - abs(vec3(s) - vec3(0.15, 0.5, 0.85)) * 2.6, 0.0) * c.a; sumColor += c.rgb * (w / max(c.a, 0.002)); sumWeight += w; } vec3 split = mix(base, sumColor / max(sumWeight, vec3(1e-4)), clamp(sumWeight * 2.0, 0.0, 1.0)); color.rgb = mix(color.rgb, clamp(split, 0.0, 1.0) * color.a, smoothstep(0.25, 1.5, spreadPx)); } fragColor = color * uSceneAlpha; } `; const Digits = ({ value }) => (

{String(value)
.padStart(2, ‘0’)
.split(”)
.map((digit, index) => (


{‘0123456789’.split(”).map(n => (
{n}
))}


))}

);

const FlexCarousel = ({
items = DEFAULT_ITEMS,
preset = ‘liquid’,
intro = ‘rise’,
cardHeight = 0.5,
gap = 12,
radius = 0,
fit = ‘natural’,
lensWidth,
lensHeight,
tilt,
roundness,
bend,
reach,
curl,
dispersion,
liquid,
followCursor,
squeeze = 0.2,
focusOnClick = true,
autoplay = false,
interval = 4,
captions = true,
captureWheel = true,
onChange,
onSelect,
className = ”,
style
}) => {
const containerRef = useRef(null);
const settingsRef = useRef(null);
const itemsRef = useRef(items);
const engineRef = useRef(null);
const callbacksRef = useRef({ onChange, onSelect });
const [active, setActive] = useState(0);
const [revealed, setRevealed] = useState(false);
const [focusOpen, setFocusOpen] = useState(false);

const base = BEND_PRESETS[preset] || BEND_PRESETS.liquid;
const pick = (value, key) => (value === undefined || value === null ? base[key] : value);

const list = items && items.length ? items : DEFAULT_ITEMS;
const itemsKey = list.map(item => item.src).join(‘|’);

useEffect(() => {
itemsRef.current = list;
callbacksRef.current = { onChange, onSelect };
settingsRef.current = {
intro,
cardHeight,
gap,
radius,
fit,
lensWidth: pick(lensWidth, ‘lensWidth’),
lensHeight: pick(lensHeight, ‘lensHeight’),
tilt: pick(tilt, ’tilt’),
roundness: pick(roundness, ’roundness’),
bend: pick(bend, ‘bend’),
reach: pick(reach, ‘reach’),
curl: pick(curl, ‘curl’),
dispersion: pick(dispersion, ‘dispersion’),
liquid: pick(liquid, ‘liquid’),
followCursor: pick(followCursor, ‘followCursor’),
squeeze,
focusOnClick,
autoplay,
interval,
captureWheel
};
engineRef.current?.wake();
});

useEffect(() => {
engineRef.current?.setItems(itemsRef.current);
}, [itemsKey]);

useEffect(() => {
const container = containerRef.current;
if (!container) return undefined;

const renderer = new Renderer({
dpr: Math.min(window.devicePixelRatio || 1, 2),
alpha: true,
premultipliedAlpha: true,
antialias: false,
depth: false
});
const gl = renderer.gl;
if (!renderer.isWebgl2) {
gl.getExtension(‘WEBGL_lose_context’)?.loseContext();
return undefined;
}
gl.clearColor(0, 0, 0, 0);
const canvas = gl.canvas;
canvas.style.display = ‘block’;
canvas.style.width = ‘100%’;
canvas.style.height = ‘100%’;
canvas.setAttribute(‘aria-hidden’, ‘true’);
container.prepend(canvas);

const cardProgram = new Program(gl, {
vertex: cardVertex,
fragment: cardFragment,
transparent: true,
depthTest: false,
depthWrite: false,
uniforms: {
tMap: { value: new Texture(gl) },
uRect: { value: [0, 0, 1, 1] },
uResolution: { value: [1, 1] },
uSize: { value: [1, 1] },
uImage: { value: [1, 1] },
uRadius: { value: 16 },
uAlpha: { value: 1 },
uReady: { value: 0 },
uShift: { value: 0 },
uDpr: { value: 1 },
uPlaceholder: { value: [0.5, 0.5, 0.5] }
}
});
cardProgram.setBlendFunc(gl.ONE, gl.ONE_MINUS_SRC_ALPHA);
const cardMesh = new Mesh(gl, { geometry: new Plane(gl), program: cardProgram });

const target = new RenderTarget(gl, {
width: 2,
height: 2,
depth: false,
minFilter: gl.LINEAR_MIPMAP_LINEAR,
magFilter: gl.LINEAR
});

const lensUniforms = {
tScene: { value: target.texture },
uResolution: { value: [1, 1] },
uDpr: { value: 1 },
uCenter: { value: [0, 0] },
uHalf: { value: [1, 1] },
uAngle: { value: 0 },
uExponent: { value: 2 },
uInner: { value: 60 },
uOuter: { value: 80 },
uFlow: { value: 0 },
uCurl: { value: 0 },
uDispersion: { value: 0 },
uStrength: { value: 0 },
uSceneAlpha: { value: 0 }
};
const lensMesh = new Mesh(gl, {
geometry: new Triangle(gl),
program: new Program(gl, {
vertex: lensVertex,
fragment: lensFragment,
uniforms: lensUniforms,
depthTest: false,
depthWrite: false
})
});

const reducedMotion = window.matchMedia?.(‘(prefers-reduced-motion: reduce)’).matches ?? false;
const anisotropy = renderer.getExtension(‘EXT_texture_filter_anisotropic’) ? 8 : 0;

let slots = [];
let width = 1;
let height = 1;
let pos = 0;
let vel = 0;
let goal = 0;
let mode = ‘spring’;
let wheelAt = 0;
let raf = 0;
let last = performance.now();
let visible = true;
let alive = true;
let dirty = true;
let activeIndex = -1;
let interactedAt = -Infinity;
let autoplayAt = performance.now();
let hasFocus = false;
let deform = 0;
let deformVel = 0;
let layout = null;
let resnap = false;
let hover = ”;
let lift = 1;
let energy = 0;
let lastPos = 0;
const lens = { x: 0, y: 0, vx: 0, vy: 0, ready: false };
const pointer = {
x: 0,
y: 0,
over: false,
down: false,
id: -1,
startX: 0,
startY: 0,
startPos: 0,
dragging: false,
touch: false,
samples: []
};
const introState = { kind: ‘none’, t: 0, running: false, done: false, readyAt: 0 };
const focus = { index: -1, pending: -1, t: 0, v: 0, target: 0 };
let instances = [];

const loadSlot = (item, index) => {
const texture = new Texture(gl, {
generateMipmaps: true,
minFilter: gl.LINEAR_MIPMAP_LINEAR,
magFilter: gl.LINEAR,
anisotropy
});
const slot = {
item,
index,
texture,
aspect: 0.8,
loaded: false,
failed: false,
ready: 0,
color: [0.5, 0.5, 0.5],
image: [1, 1],
dispose: () => {}
};
const image = new Image();
image.crossOrigin = ‘anonymous’;
image.decoding = ‘async’;
image.onload = () => {
if (!alive || !slots.includes(slot)) return;
texture.image = image;
texture.update();
slot.image = [image.naturalWidth || 1, image.naturalHeight || 1];
slot.aspect = slot.image[0] / slot.image[1];
try {
const probe = document.createElement(‘canvas’);
probe.width = 8;
probe.height = 8;
const ctx = probe.getContext(‘2d’, { willReadFrequently: true });
if (ctx) {
ctx.drawImage(image, 0, 0, 8, 8);
const data = ctx.getImageData(0, 0, 8, 8).data;
const avg = [0, 0, 0];
for (let i = 0; i < data.length; i += 4) { avg[0] += data[i]; avg[1] += data[i + 1]; avg[2] += data[i + 2]; } slot.color = avg.map(v => v / 64 / 255);
}
} catch {
slot.color = [0.5, 0.5, 0.5];
}
slot.loaded = true;
dirty = true;
start();
};
image.onerror = () => {
if (!alive) return;
slot.failed = true;
dirty = true;
start();
};
image.src = item.src;
slot.dispose = () => {
image.onload = null;
image.onerror = null;
gl.deleteTexture(texture.texture);
};
return slot;
};

const setItems = next => {
slots.forEach(slot => slot.dispose());
slots = next.map(loadSlot);
activeIndex = -1;
layout = null;
resnap = true;
focus.target = 0;
focus.t = 0;
focus.v = 0;
focus.pending = -1;
setFocusOpen(false);
introState.readyAt = performance.now();
dirty = true;
start();
};

const metrics = s => {
const cardH = Math.max(24, s.cardHeight * height);
const fixed = FIT_ASPECT[s.fit];
const widths = slots.map(slot => (fixed || slot.aspect) * cardH);
const centers = [];
let cursor = 0;
for (let i = 0; i < widths.length; i++) { centers.push(cursor + widths[i] / 2); cursor += widths[i] + s.gap; } return { cardH, widths, centers, gap: s.gap, loop: Math.max(cursor, 1) }; }; const nearest = (m, at) => {
let best = 0;
let bestDist = Infinity;
for (let i = 0; i < m.centers.length; i++) { const dist = Math.abs(wrap(m.centers[i] - at, m.loop)); if (dist < bestDist) { bestDist = dist; best = i; } } return best; }; const snapPoint = (m, at) => {
const i = nearest(m, at);
return at + wrap(m.centers[i] – at, m.loop);
};

const remap = (from, to, at) => {
const i = nearest(from, at);
const offset = wrap(at – from.centers[i], from.loop);
const cycles = Math.round((at – offset – from.centers[i]) / from.loop);
return cycles * to.loop + to.centers[i] + offset * (to.widths[i] / from.widths[i]);
};

const step = (m, delta) => {
let at = snapPoint(m, goal);
let index = nearest(m, at);
const n = m.centers.length;
for (let k = 0; k < Math.abs(delta); k++) { const next = (index + (delta > 0 ? 1 : n – 1)) % n;
const distance =
delta > 0
? m.widths[index] / 2 + m.gap + m.widths[next] / 2
: -(m.widths[next] / 2 + m.gap + m.widths[index] / 2);
at += distance;
index = next;
}
goal = at;
mode = ‘spring’;
dirty = true;
start();
};

const goTo = (m, index) => {
const i = ((index % m.centers.length) + m.centers.length) % m.centers.length;
goal = goal + wrap(m.centers[i] – goal, m.loop);
mode = ‘spring’;
dirty = true;
start();
};

const openFocus = index => {
focus.index = index;
focus.pending = -1;
focus.target = 1;
setFocusOpen(true);
dirty = true;
start();
};

const closeFocus = () => {
focus.pending = -1;
if (focus.target === 0) return false;
focus.target = 0;
setFocusOpen(false);
dirty = true;
start();
return true;
};

const skipIntro = () => {
if (introState.running) introState.t = 1;
};

const introEffects = () => {
const t = introState.running ? introState.t : introState.done ? 1 : 0;
const e = { sceneAlpha: 1, strength: 1, card: null };
if (!introState.done && !introState.running) {
e.sceneAlpha = 0;
e.strength = 0;
return e;
}
if (t >= 1) return e;
const kind = introState.kind;
if (kind === ‘rise’) {
e.strength = easeInOut((t – 0.3) / 0.65);
e.card = rel => {
const delay = Math.min(Math.abs(rel) / (width * 0.6), 1) * 0.34;
const local = clamp01((t – delay) / 0.6);
return {
alpha: clamp01(local * 4),
x: 0,
y: (1 – easeOutQuint(local)) * height * 0.62,
scale: 0.5 + 0.5 * easeInOut((local – 0.18) / 0.82)
};
};
} else if (kind === ‘bloom’) {
e.strength = easeInOut((t – 0.2) / 0.8);
e.card = rel => {
const delay = Math.min(Math.abs(rel) / (width * 0.6), 1) * 0.25;
const local = easeOut((t – delay) / 0.55);
return { alpha: local, x: 0, y: 0, scale: 0.92 + 0.08 * local };
};
} else if (kind === ‘spin’) {
e.sceneAlpha = easeOut(t / 0.25);
e.strength = easeOut((t – 0.55) / 0.45);
} else if (kind === ‘deal’) {
e.strength = easeOut((t – 0.45) / 0.5);
e.card = rel => {
const spread = Math.min(Math.abs(rel) / (width * 0.6), 1) * 0.3;
const local = easeOut((t – 0.12 – spread) / 0.5);
return { alpha: easeOut((t – spread) / 0.12), x: -rel * (1 – local), y: 0, scale: 1 };
};
} else {
e.sceneAlpha = easeOut(t);
e.strength = easeOut(t);
}
return e;
};

const beginIntro = (s, m) => {
const kind = reducedMotion && s.intro !== ‘none’ ? ‘fade’ : s.intro;
introState.kind = INTRO_DURATION[kind] ? kind : ‘none’;
introState.running = introState.kind !== ‘none’;
introState.done = !introState.running;
introState.t = 0;
if (introState.done) setRevealed(true);
if (introState.kind === ‘spin’) {
const distance = m.loop * 1.6 + width;
pos = goal + distance;
vel = -distance * 3;
mode = ‘spring’;
}
};

const resize = () => {
width = Math.max(1, container.clientWidth);
height = Math.max(1, container.clientHeight);
renderer.dpr = Math.min(window.devicePixelRatio || 1, 2, Math.sqrt(PIXEL_BUDGET / (width * height)));
renderer.setSize(width, height);
target.setSize(Math.max(2, Math.round(width * renderer.dpr)), Math.max(2, Math.round(height * renderer.dpr)));
lensUniforms.tScene.value = target.texture;
dirty = true;
start();
};

const frame = now => {
raf = 0;
if (!alive) return;
const s = settingsRef.current;
const dt = Math.min(0.05, Math.max(0.001, (now – last) / 1000));
last = now;
if (!s || !slots.length) {
if (visible) raf = requestAnimationFrame(frame);
return;
}

const m = metrics(s);
const n = slots.length;
let animating = false;

if (resnap) {
goal = snapPoint(m, goal);
pos = goal;
vel = 0;
resnap = false;
} else if (layout && layout.loop !== m.loop) {
pos = remap(layout, m, pos);
goal = remap(layout, m, goal);
pointer.startPos = pos + (pointer.x – pointer.startX);
animating = true;
}
layout = m;

if (!introState.running && !introState.done) {
const allSettled = slots.every(slot => slot.loaded || slot.failed);
if (allSettled || now – introState.readyAt > 3500) {
goal = snapPoint(m, goal);
pos = goal;
beginIntro(s, m);
}
}
if (introState.running) {
introState.t = Math.min(1, introState.t + dt / (INTRO_DURATION[introState.kind] || 1));
if (introState.t >= 1) {
introState.running = false;
introState.done = true;
setRevealed(true);
}
animating = true;
}

if (mode === ‘wheel’ && now – wheelAt > 150) {
goal = snapPoint(m, goal);
mode = ‘spring’;
}
if (!pointer.dragging) {
const spinning = introState.running && introState.kind === ‘spin’;
const stiffness = spinning ? 9 : mode === ‘wheel’ ? 80 : 55;
const damping = 2 * Math.sqrt(stiffness);
const steps = Math.ceil(dt / (1 / 240));
const h = dt / steps;
for (let i = 0; i < steps; i++) { const acc = stiffness * (goal - pos) - damping * vel; vel += acc * h; pos += vel * h; } if (Math.abs(goal - pos) < 0.05 && Math.abs(vel) < 0.5) { pos = goal; vel = 0; } else { animating = true; } } else { animating = true; } if (Math.abs(pos) > m.loop * 8) {
const shift = Math.round(pos / m.loop) * m.loop;
pos -= shift;
goal -= shift;
pointer.startPos -= shift;
}

const current = nearest(m, pos);
if (current !== activeIndex) {
activeIndex = current;
setActive(current);
callbacksRef.current.onChange?.(current, itemsRef.current[current]);
}

if (focus.pending >= 0 && mode === ‘spring’ && Math.abs(goal – pos) < 1.5 && Math.abs(vel) < 30) { if (current === focus.pending) openFocus(current); else focus.pending = -1; } if ( s.autoplay && !reducedMotion && introState.done && focus.target === 0 && focus.t < 0.01 && !pointer.over && !pointer.down && !hasFocus && mode === 'spring' && Math.abs(goal - pos) < 1 && now - interactedAt > 3000 &&
now – autoplayAt > s.interval * 1000
) {
autoplayAt = now;
step(m, 1);
}
if (s.autoplay && !reducedMotion) animating = true;

const travel = Math.abs(pos – lastPos) / dt;
lastPos = pos;
const energyTarget = reducedMotion ? 0 : Math.min(travel / 2600, 1);
energy += (energyTarget – energy) * (1 – Math.exp(-dt / (energyTarget > energy ? 0.07 : 0.35)));
if (energy > 0.001) animating = true;
const liquidAmount = reducedMotion ? 0 : s.liquid;
const push = Math.max(-1, Math.min(1, vel / 2200));
const deformStiffness = 120;
const deformDamping = 2 * Math.sqrt(deformStiffness) * 0.32;
deformVel += (deformStiffness * (push – deform) – deformDamping * deformVel) * dt;
deform += deformVel * dt;
if (Math.abs(deform) > 0.0005 || Math.abs(deformVel) > 0.005) animating = true;

const focusStiffness = 64;
focus.v += (focusStiffness * (focus.target – focus.t) – 2 * Math.sqrt(focusStiffness) * focus.v) * dt;
focus.t += focus.v * dt;
if (Math.abs(focus.target – focus.t) < 0.0005 && Math.abs(focus.v) < 0.001) { focus.t = focus.target; focus.v = 0; } else { animating = true; } const focusAmount = clamp01(focus.t); const focusEase = easeInOut(focusAmount); const focusW = focus.index >= 0 && focus.index < n ? m.widths[focus.index] : m.cardH; const focusScale = Math.max(1, Math.min(1.3, (height * 0.84) / m.cardH, (width * 0.92) / focusW)); const nextLift = 1 + (focusScale - 1) * focusEase; if (Math.abs(nextLift - lift) > 0.0005) {
lift = nextLift;
container.style.setProperty(‘–flex-carousel-lift’, lift.toFixed(4));
}

const effects = introEffects();

const homeX = width / 2;
const homeY = height / 2;
const follow = s.followCursor && pointer.over && !pointer.dragging && !pointer.touch && focus.target === 0;
const aimX = follow ? pointer.x : homeX;
const aimY = follow ? pointer.y : homeY;
if (!lens.ready) {
lens.x = homeX;
lens.y = homeY;
lens.ready = true;
}
const lensK = 110;
const lensC = 2 * Math.sqrt(lensK) * 0.8;
lens.vx += (lensK * (aimX – lens.x) – lensC * lens.vx) * dt;
lens.vy += (lensK * (aimY – lens.y) – lensC * lens.vy) * dt;
lens.x += lens.vx * dt;
lens.y += lens.vy * dt;
if (Math.abs(aimX – lens.x) + Math.abs(aimY – lens.y) > 0.2 || Math.abs(lens.vx) + Math.abs(lens.vy) > 0.5)
animating = true;

const cardH = m.cardH;
let halfW = (s.lensWidth * width) / 2;
let halfH = (s.lensHeight * width) / 2;
const squash = Math.abs(deform) * liquidAmount;
halfW *= 1 + squash * 0.16;
halfH *= 1 – squash * 0.08;
const lensX = lens.x – deform * 14 * liquidAmount;

for (let i = 0; i < n; i++) { const slot = slots[i]; if (slot.loaded && slot.ready < 1) { slot.ready = Math.min(1, slot.ready + dt / 0.45); animating = true; } } const waiting = !introState.done; if (dirty || animating || pointer.dragging) { dirty = false; instances = []; const dpr = renderer.dpr; cardProgram.uniforms.uResolution.value = [width, height]; cardProgram.uniforms.uDpr.value = dpr; cardProgram.uniforms.uRadius.value = s.radius; const shrink = 1 - clamp01(s.squeeze) * energy; const draws = []; for (let i = 0; i < n; i++) { const w = m.widths[i]; const baseRel = wrap(m.centers[i] - pos, m.loop); for (let k = -3; k <= 3; k++) { const rel = baseRel + k * m.loop; if (Math.abs(rel) - w / 2 > width + 40) continue;
const fx = effects.card ? effects.card(rel) : null;
let x = homeX + rel + (fx ? fx.x : 0);
let scale = shrink * (fx ? fx.scale : 1);
let alpha = fx ? fx.alpha : 1;
if (focusAmount > 0) {
if (i === focus.index && Math.abs(rel) < w) { scale *= 1 + (focusScale - 1) * focusEase; } else { const order = Math.min(Math.abs(rel) / width, 1) * 0.25; const part = easeInOut(focusAmount * 1.25 - order); x += Math.sign(rel) * part * width * 0.7; alpha *= 1 - part; } } const cw = w * scale; if (alpha <= 0.001 || x + cw / 2 < -40 || x - cw / 2 > width + 40) continue;
draws.push({ i, rel, x, y: homeY + (fx ? fx.y : 0), cw, ch: cardH * scale, alpha });
}
}
draws.sort((a, b) => Math.abs(b.rel) – Math.abs(a.rel));
let first = true;
for (const draw of draws) {
const slot = slots[draw.i];
cardProgram.uniforms.tMap.value = slot.texture;
cardProgram.uniforms.uRect.value = [draw.x, draw.y, draw.cw + 2, draw.ch + 2];
cardProgram.uniforms.uSize.value = [draw.cw, draw.ch];
cardProgram.uniforms.uImage.value = slot.image;
cardProgram.uniforms.uAlpha.value = draw.alpha;
cardProgram.uniforms.uReady.value = slot.ready;
cardProgram.uniforms.uShift.value = reducedMotion ? 0 : Math.max(-1, Math.min(1, draw.rel / (width * 0.75)));
cardProgram.uniforms.uPlaceholder.value = slot.color;
renderer.render({ scene: cardMesh, target, clear: first });
first = false;
instances.push({
index: draw.i,
x0: draw.x – draw.cw / 2,
x1: draw.x + draw.cw / 2,
y0: draw.y – draw.ch / 2,
y1: draw.y + draw.ch / 2
});
}
if (first) {
renderer.bindFramebuffer(target);
gl.viewport(0, 0, target.width, target.height);
gl.clear(gl.COLOR_BUFFER_BIT);
}
renderer.bindFramebuffer();
target.texture.bind();
gl.generateMipmap(gl.TEXTURE_2D);

lensUniforms.uResolution.value = [width, height];
lensUniforms.uDpr.value = dpr;
lensUniforms.uCenter.value = [lensX, lens.y];
lensUniforms.uHalf.value = [Math.max(halfW, 1), Math.max(halfH, 1)];
lensUniforms.uAngle.value = (s.tilt * Math.PI) / 180;
lensUniforms.uExponent.value = 2 + Math.pow(1 – clamp01(s.roundness), 1.5) * 10;
const spanW = Math.max(halfW, 1);
const spanH = Math.max(halfH, 1);
const inner = Math.max(4, s.reach * (spanW + spanH) * 0.5);
lensUniforms.uInner.value = inner;
lensUniforms.uOuter.value = inner * 1.6;
lensUniforms.uFlow.value = s.bend * (spanW + spanH) * 0.45;
lensUniforms.uCurl.value = s.curl === ‘rise’ ? 1 : s.curl === ‘fall’ ? -1 : 0;
lensUniforms.uDispersion.value = s.dispersion * 0.12 * (1 + Math.abs(deform) * liquidAmount * 1.2);
lensUniforms.uStrength.value = effects.strength * (1 – focusEase);
lensUniforms.uSceneAlpha.value = effects.sceneAlpha;
renderer.render({ scene: lensMesh });
}

let nextHover = ”;
if (pointer.over && !pointer.dragging && introState.done && s.focusOnClick) {
const hit = instances.find(
inst => pointer.x >= inst.x0 && pointer.x <= inst.x1 && pointer.y >= inst.y0 && pointer.y <= inst.y1 ); if (focus.target > 0) nextHover = ‘close’;
else if (hit) nextHover = ‘open’;
}
if (nextHover !== hover) {
hover = nextHover;
if (hover) container.setAttribute(‘data-hover’, hover);
else container.removeAttribute(‘data-hover’);
}

if (visible && (animating || waiting || dirty || pointer.down)) raf = requestAnimationFrame(frame);
};

const start = () => {
if (raf || !visible || !alive) return;
last = performance.now();
raf = requestAnimationFrame(frame);
};

const localPoint = e => {
const rect = container.getBoundingClientRect();
return [e.clientX – rect.left, e.clientY – rect.top];
};

const onPointerDown = e => {
if (e.button !== undefined && e.button > 0) return;
skipIntro();
const [x, y] = localPoint(e);
pointer.down = true;
pointer.id = e.pointerId;
pointer.touch = e.pointerType === ‘touch’;
pointer.startX = x;
pointer.startY = y;
pointer.x = x;
pointer.y = y;
pointer.startPos = pos;
pointer.dragging = false;
pointer.samples = [{ x, t: performance.now() }];
interactedAt = performance.now();
if (Math.abs(vel) > 40) {
goal = pos;
vel = 0;
}
dirty = true;
start();
};

const onPointerMove = e => {
const [x, y] = localPoint(e);
pointer.x = x;
pointer.y = y;
pointer.over = true;
if (pointer.down && e.pointerId === pointer.id) {
const dx = x – pointer.startX;
const dy = y – pointer.startY;
const slop = pointer.touch ? 10 : 5;
if (!pointer.dragging) {
if (pointer.touch && Math.abs(dy) > slop && Math.abs(dy) > Math.abs(dx)) {
pointer.down = false;
return;
}
if (Math.abs(dx) > slop) {
pointer.dragging = true;
pointer.startX = x;
pointer.startPos = pos;
closeFocus();
try {
container.setPointerCapture(e.pointerId);
} catch {
pointer.dragging = true;
}
container.setAttribute(‘data-dragging’, ”);
}
}
if (pointer.dragging) {
pos = pointer.startPos – (x – pointer.startX);
goal = pos;
vel = 0;
const now = performance.now();
pointer.samples.push({ x, t: now });
while (pointer.samples.length > 2 && now – pointer.samples[0].t > 100) pointer.samples.shift();
}
}
dirty = true;
start();
};

const onPointerUp = e => {
if (!pointer.down || e.pointerId !== pointer.id) return;
pointer.down = false;
container.removeAttribute(‘data-dragging’);
const s = settingsRef.current;
if (!s) return;
const m = metrics(s);
interactedAt = performance.now();
if (pointer.dragging) {
pointer.dragging = false;
const now = performance.now();
const first = pointer.samples[0];
const lastSample = pointer.samples[pointer.samples.length – 1];
let velocity = 0;
if (first && lastSample && lastSample.t > first.t && now – lastSample.t < 70) { velocity = -((lastSample.x - first.x) / (lastSample.t - first.t)) * 1000; } vel = velocity; const landing = snapPoint(m, pos + velocity * 0.32); goal = landing; if (Math.abs(velocity) > 400 && Math.abs(landing – pos) < 1) step(m, velocity > 0 ? 1 : -1);
mode = ‘spring’;
start();
return;
}
if (closeFocus()) return;
const [x, y] = localPoint(e);
const hit = instances.find(inst => x >= inst.x0 && x <= inst.x1 && y >= inst.y0 && y <= inst.y1); if (!hit) return; if (hit.index === activeIndex && Math.abs(goal - pos) < 2) { callbacksRef.current.onSelect?.(hit.index, itemsRef.current[hit.index]); if (s.focusOnClick) openFocus(hit.index); } else { const rel = (hit.x0 + hit.x1) / 2 - width / 2; goal = snapPoint(m, pos + rel); mode = 'spring'; if (s.focusOnClick) focus.pending = hit.index; start(); } }; const onPointerLeave = () => {
pointer.over = false;
dirty = true;
start();
};

const onPointerCancel = () => {
pointer.down = false;
pointer.dragging = false;
container.removeAttribute(‘data-dragging’);
const s = settingsRef.current;
if (!s) return;
goal = snapPoint(metrics(s), pos);
mode = ‘spring’;
start();
};

const onWheel = e => {
const s = settingsRef.current;
if (!s || e.ctrlKey) return;
let dx = e.deltaX;
let dy = e.deltaY;
if (e.shiftKey && Math.abs(dx) < Math.abs(dy)) { dx = dy; dy = 0; } const unit = e.deltaMode === 1 ? 16 : e.deltaMode === 2 ? height : 1; const horizontal = Math.abs(dx) > Math.abs(dy);
if (!horizontal && !s.captureWheel) return;
e.preventDefault();
skipIntro();
interactedAt = performance.now();
if (closeFocus()) return;
const delta = Math.max(-120, Math.min(120, (horizontal ? dx : dy) * unit));
goal += delta * 1.25;
mode = ‘wheel’;
wheelAt = performance.now();
start();
};

const onKeyDown = e => {
const s = settingsRef.current;
if (!s) return;
const m = metrics(s);
if (e.key === ‘ArrowRight’ || e.key === ‘ArrowDown’) {
e.preventDefault();
skipIntro();
closeFocus();
interactedAt = performance.now();
step(m, 1);
} else if (e.key === ‘ArrowLeft’ || e.key === ‘ArrowUp’) {
e.preventDefault();
skipIntro();
closeFocus();
interactedAt = performance.now();
step(m, -1);
} else if (e.key === ‘Home’) {
e.preventDefault();
closeFocus();
goTo(m, 0);
} else if (e.key === ‘End’) {
e.preventDefault();
closeFocus();
goTo(m, slots.length – 1);
} else if (e.key === ‘Escape’) {
if (closeFocus()) e.preventDefault();
} else if (e.key === ‘Enter’ || e.key === ‘ ‘) {
e.preventDefault();
if (closeFocus() || activeIndex < 0) return; callbacksRef.current.onSelect?.(activeIndex, itemsRef.current[activeIndex]); if (s.focusOnClick) openFocus(activeIndex); } }; const onFocus = () => {
hasFocus = true;
};
const onBlur = () => {
hasFocus = false;
};
const onVisibility = () => {
if (!document.hidden) start();
};

container.addEventListener(‘pointerdown’, onPointerDown);
container.addEventListener(‘pointermove’, onPointerMove);
container.addEventListener(‘pointerup’, onPointerUp);
container.addEventListener(‘pointerleave’, onPointerLeave);
container.addEventListener(‘pointercancel’, onPointerCancel);
container.addEventListener(‘wheel’, onWheel, { passive: false });
container.addEventListener(‘keydown’, onKeyDown);
container.addEventListener(‘focus’, onFocus);
container.addEventListener(‘blur’, onBlur);
document.addEventListener(‘visibilitychange’, onVisibility);

const resizeObserver = new ResizeObserver(resize);
resizeObserver.observe(container);
const intersectionObserver = new IntersectionObserver(([entry]) => {
visible = entry.isIntersecting;
start();
});
intersectionObserver.observe(container);

engineRef.current = {
wake: () => {
dirty = true;
start();
},
setItems
};

resize();
setItems(itemsRef.current);

return () => {
alive = false;
visible = false;
engineRef.current = null;
cancelAnimationFrame(raf);
resizeObserver.disconnect();
intersectionObserver.disconnect();
container.removeEventListener(‘pointerdown’, onPointerDown);
container.removeEventListener(‘pointermove’, onPointerMove);
container.removeEventListener(‘pointerup’, onPointerUp);
container.removeEventListener(‘pointerleave’, onPointerLeave);
container.removeEventListener(‘pointercancel’, onPointerCancel);
container.removeEventListener(‘wheel’, onWheel);
container.removeEventListener(‘keydown’, onKeyDown);
container.removeEventListener(‘focus’, onFocus);
container.removeEventListener(‘blur’, onBlur);
document.removeEventListener(‘visibilitychange’, onVisibility);
slots.forEach(slot => slot.dispose());
slots = [];
gl.getExtension(‘WEBGL_lose_context’)?.loseContext();
if (canvas.parentNode) canvas.parentNode.removeChild(canvas);
};
}, []);

const current = list[active] || list[0];
const label = current ? current.title || current.alt || `Image ${active + 1}` : ”;

return (

);
};

export default FlexCarousel;